Other versions exist on this site from various publications. This one is from the Radio Electronics Experimenter from 1990. The bargraph circuit uses the UAA170.
We found this telephone amplifier in a European publication from the 1980s. The transistor can be...
This circuit is one of many that we have in our section. It was taken from the Electronics...
This circuit is from a 1980s Motorola documentation. The circuit can be set to fire from 60 to 120...